For example, Patent Document 1 below discloses an oil supply structure of a clutch device of a motorcycle engine. The clutch device includes a clutch inner member, a clutch outer member, a plurality of first and second frictional power transmitting members belonging to the clutch inner member and the clutch outer member, respectively, a clutch pressure member, and a clutch lifter member. The clutch inner member is disposed on one end portion of a power transmission shaft. The clutch outer member is disposed coaxially with the clutch inner member. The frictional power transmitting members are provided on the clutch inner member and the clutch outer member. The first and second frictional power transmitting members are alternately stacked between the clutch inner member and the clutch outer member. The clutch pressure member is disposed to axially face the clutch inner member. The clutch pressure member is operative to bring the frictional power transmitting members into pressure contact to connect the clutch device. The clutch lifter member includes a flange portion acting to axially shift the clutch pressure member in a direction to disconnect the clutch device. One end portion of the power transmission shaft has a distal end adjacent to an oil supply device or portion adjacent to the flange portion.
In the oil supply structure of the clutch device disclosed in Patent Document 1 below, the oil supply portion is provided adjacent to the distal end of the one end portion of the power transmission shaft. It is desired in such oil supply structure to improve oil supply performance to the frictional power transmitting members, aiming at a further sufficient oil supply to a far-side in the axial direction of the clutch device.